For other people like me, who didn't know what this was referring to, I think this is the post brudgers is talking about http://www.hanselman.com/blog/DarkMatterDevelopersTheUnseen9...
Except for the past few weeks, I've listened to all of Hanselman's Hansel Minutes podcasts, started in summer 2014 and got current about a year ago. Interesting content while driving in my opinion.
Anyway, he uses the term fairly regularly as a way of grounding discussions when they drift toward the-newest-shinyest or what-the-cool-kids-use. I think it's a helpful construct when thinking about "what should I use" since the best answer usually isn't React Native.
A real life example of what Scott Hanselman calls "a dark matter programmer"...he uses "the chief software architect of the Nebraska division of forestry."